The invention set forth in this specification pertains to a new and improved switch. More specifically it pertains to what may be referred to as an electrical or electronic switch which does not employ any physically moving parts and which is adapted to be turned on and off through engagement with the hand of a user.
The invention is primarily intended to be utilized in turning on and off various types of electrically powered instruments having handles which are adapted to be engaged by the hand of the user during utilization of the instrument. Such instruments may be constructed and utilized for a wide variety of different, diverse purposes. Such instruments may utilize internal batteries in order to obtain electric power or may be connected to an appropriate power source through the use of a conventional electric cord. Normally such instruments include a conventional type of switch which has to be actuated in order to turn the instrument on or off.
It has been recognized that the utilization of such switches in hand held electrically powered instruments is relatively disadvantageous. One reason for this pertains to the usual reliability problems associated with conventional switches employing mechanical movement. The use of such switches in instruments as described is also relatively disadvantageous because of the possibility that the user of an instrument may forget to or may neglect to turn the switch on such an instrument off when the instrument itself is not being utilized.
The recognition of the latter has led to the development of various instruments in which the switch is located so that when the instrument is removed from the hand the switch will automatically move to an off position. It is also known to construct instruments as described with a trigger mechanism utilized in conjunction with the handle of an instrument operatively connected to a switch so that the instrument may be turned on and off through the actuation of the trigger mechanism. While utilitarian expedients of these types are disadvantageous because of the reliability problems associated with any mechanical switch as briefly noted in the preceding.
Frequently the inclusion of a switch actuated by a trigger mechanism in an instrument as noted is disadvantageous for another reason. Frequently it is necessary or desirable to utilize a trigger in such an instrument to control the operation and/or utilization of the instrument in other than an on/off type manner. In general, the use of a multifunction trigger mechanism to accomplish switch actuation and to accomplish another control function tends to make an instrument unnecessarily complex. This in turn tends to affect instrument costs and reliability.
In the past it has been proposed to avoid the reliability problems associated with mechanical switches and to avoid the possibility of an instrument being laid aside while remaining turned on through the use of various types of proximity switches. While expedients of this type are also considered to be utilitarian they are also considered to be relatively undesirable. This is because an instrument as noted may be laid down upon a table or work bench or the like in such a manner that any proximity switch mechanism within the instrument is sufficiently close to one or more objects so as to be actuated by such objects. This, of course, will have the effect of leaving the instrument on when the instrument itself is not in use.